Heat a wok and add the sesame seeds.
Stir over medium-high heat until they are lightly toasted.
Cool and crush the seeds with a mortar and pestle or food blender.
Mix with the miso and sugar.
Wash the spinach and drain well.
Heat a wok or frying pan and add the oil.
Stir-fry the spinach just until it collapses.
Remove from the wok.
Stir the miso and sesame paste into the spinach.
Serve hot or cold.